Nowadays, with the development of green and environment-friendly electrical and electronic products (e.g., mobile phones or computers), small, thin, and fine portable electrical and electronic products need to be produced, with increasingly higher requirements for their internal structure refinement.
Currently, ink is printed on inner and outer surfaces of outer and intermediate shells of an electronic product to produce a circuit instead of having a conductive circuit board inside the electronic product, thus saving space inside the electronic product and reducing the size of the electronic product. Meanwhile, since the circuit and the inner and outer surfaces of the outer shell of the electronic product are fused together into a three-dimensional carrier, the need for cumbersome processes such as surface mount technology is eliminated, fewer apparatuses are used, and costs are saved, and therefore this technique is applied to high-precision electrical and electronic products with high evaluation.
However, a conventional ink composition is used at a high temperature of 500° C. to 1000° C., and thus may be only applied to a rubber substrate rather than other substrates such as a polypropylene substrate or a polyethylene substrate commonly used in electronic products. Materials of most electronic products may be easy to deform or carbonize at this high temperature, thus affecting the electronic products adversely and limiting the application of the ink composition. Moreover, fine circuits with a small pitch may not be produced. Furthermore, ink layers formed from the ink composition are instable in ink density, and circuit boards formed from the ink composition are instable and poor in conductivity, thus restricting their practical applications.